What does overcoming personal tragedy have to do with being a good President?

Joe Biden, with his two sons, and wife, Neilia, who was killed in an automobile accident one month before he took office.

Joe Biden has been a Senator for 36 years. He has vast understanding of constitutional law and foreign affairs, among other topics. But his most important qualification for Vice President is that his wife and daughter were killed and two sons badly injured in a tragic auto accident in 1972. At least that is the impression you get from listening to Barack Obama and other Democrats as they tout Obama's choice for Vice President. By the same standard, Biden's second most important qualification appears to be that in 1988 he suffered two life-threatening brain aneurysms.